| 摘要 |
A navigation apparatus for searching for a route from a place of departure to a destination includes an information storage unit storing map data in a hierarchical structure, a route-searching unit for retrieving the map data from the information storage unit, searching for a route within a predetermined area on the departure side and on the destination side, and obtaining a route with the lowest cost in the range of overlapped search areas, and a control unit for controlling the search by the route-searching unit. The control unit updates the registered cost for the lowest cost route when the cost of the route of lowest cost obtained by searching up to a higher level within the hierarchy is smaller than that previously registered cost.
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